#include <iostream>
using namespace std;
const int N = 30;
int dp[N];
int main() {
    for(int i=1;i<=20;i++)
    {
        dp[i]=1;
        for(int j=1;j<i;j++){
            dp[i]+=dp[j];
        }
    }
    int n;
    cin >> n;
    cout << dp[n] << endl;
    return 0;
}